A veteran of the Sri Lankan domestic circuit, the Colombo-born Gunaratne has made over 100 first-class appearances. A batting allrounder, he made his first T20 appearance in 2004 for Chilaw Marians. He was one of Ruhuna's heroes in the 2011 Inter-Provincial T20. He top-scored for his side with 83 and picked up 1 for 17 in the big final against Wayamba. He also hit the winning runs in the Super Over that earned Ruhuna a spot in the Champions League T20 in 2011.